It is well known to provide catheters which permit the injection of fluids in the body as well as measurement of electrical activity of different organs or muscles. While these prior art catheters have been used in various areas of the body, they have not been used in applying medication to and detecting evoked responses from the spinal epidural area.
Grausz U.S. Pat. No. 3,817,241 shows a catheter which both supplies a fluid, such as from an I.V. bottle 27, and provides a probe which may extend into the patient's artery or vein. Probe 16 and 17 senses EKG activity and/or provides shocking for pacing of the heart.
Bradley U.S. Pat. No. 4,073,287 et al. teaches the use of a catheter for performing urethral profilometry. The catheter is provided with a fluid entrance 22 for inserting fluid into the body, and a connector plug 16 which is connected to electrodes 18 and 19. The electrodes 18 and 19 band around the tube, and provide electrical contact to the urethral tissue.
White U.S. Pat. No. 4,360,031 shows the use of a drug dispensing and irrigatable electrode. This device is for use in heart treatment.
U.S. Pat. Nos. 4,819,661 to Heil, Jr. et al., 4,013,317 to Bruno, 4,832,048 to Cohen and 4,711,251 to Stokes show other examples of catheters, suction devices, and probes which include electrical leads for testing of body reactions or functions.
The use of electrodes for electrophysiological monitoring of the spinal cord during spinal surgery, and particularly for measurement of motor and somatosensory function, is known (Jones et al, "A system for the electrophysiological monitoring of the spinal cord during operations for scoliosis," J. Bone Joint Surg., 65-B, 134-139 (1983); Boyd et al, "A method of monitoring function in corticospinal pathways during scoliosis surgery with a note on motor conduction velocities," J. Neurol. Neurosurg. Psychiat., 49, 251-257 (1986)). For this purpose electrodes are placed in the spinal cord area during surgery. Machida et al, "Spinal cord monitoring--Electrophysiological measures of sensory and motor function during spinal surgery," Spine, 10 (1985), disclose the use of two sets of electrodes on the spinal cord during surgery, one for transmitting stimuli and the other for recording evoked potential. However, two separate electrode arrays were necessary for this purpose.